The attack did not seem to be linked to any other content within the episode, which saw Benedict Cumberbatch’s character struggling to write a Best Man speech for Dr Watson’s wedding day.

^{Mayor of London Boris Johnson (Andrew Parson)}

During the opening sequence newspapers reporting on bank robberies by the “Water Gang” flashed up on the screen as the police officers involved become increasingly frustrated at being unable to catch the criminals.

The first, visible for just a matter of second, included on the bottom of the page the story headlined “Thames to become a watery motorway”.

The text read: “A new plan by the current Mayor of London to turn the Thames into a bustling water-bound version of the M25 has hit rush-hour traffic as reaction has been damper than a dip in the rat-infested drink.

“The hair-brained (sic) scheme involved chartering disused boats, paying for their conversion into a version of London’s famous bus, the Routemaster, but this plan has already foundered after pilot schemes revealed that customers were walking straight off the boat and into the icy currents of the Thames.

“When asked to explain how the system might move forward, or even be profitable, or perhaps even to explain the point, the Mayor, who was at a self-promotion event, was found to be dithering, incoherent, and self-interested.

“He said, “Well the fact of the matter is that Londoners need to recognise our great naval history, rather than naval (sic) gazing, and this will get the traffic moving while invoking memories of Nelson and the like. Huzzar!”

“The plan joins a long list of bizarre concepts including the recently-mocked concept of putting an airport in the middle of the estuary.”